1. Field of the Invention
This invention relates to workstock forming devices such as pipe nipple threading apparatuses and a method of sequentially forming the ends of workstock blanks without reversing the blanks. Typically, the circumferential exterior of both ends of multiple pipe nipple blanks can be threaded using an indexible turntable. In a preferred embodiment the apparatus and method of this invention includes a loading servo or cylinder which linearly contacts multiple workstock such as pipe nipple blanks and successively loads individual blanks onto a rotatable, indexible turntable. The turntable is designed to rotate and index at a specified angle, typically 45 degrees, and carries a pair of clamps or vises at opposite peripheral edges, a first one of which vises initially receives a first blank, the turntable then rotates and aligns the first blank with a first forming spindle, such as a threading spindle, which extends a head to engage and form or thread the exterior circumference of one end of the first blank as it is gripped by the vise. The turntable subsequently rotates back into alignment with the loading servo or cylinder, receives a second blank from the loading cylinder and rotates to align the second blank with the first spindle, which forms or threads one end of the second blank as it is seated in the first vise. Simultaneously, the first blank is forced by the second blank into a guide tube lying across a diameter of the turntable and extending between the vises and the turntable continues to rotate and ultimately align the unformed ends of the first and subsequent blanks with a second forming spindle, which similarly forms or threads the unthreaded ends of these blanks. The first and succeeding blanks, formed or threaded at each end, are then individually displaced from the guide tube and deposited in a hopper or at an inspection station and the cycle is repeated. The components of the workstock forming apparatus, typified herein by a pipe nipple threading device, may be sequentially activated and controlled by a programmable controller, either manually, or automatically, by a pre-programmed computer.
2. Description of the Prior Art
Various automated devices for forming, machining or threading items such as pipes, are known in the art. U.S. Pat. No. 4,301,581, dated Nov. 24, 1981, to Eugen Bader and Kurt Jauch, discloses a "Method and Apparatus for the Production of Turned Workpieces on Multi-Station Machine Tools". A rod stock is clamped by a clamping device on the machine. A rod section is then severed at a distance from the clamping device corresponding to a multiple of the machining length, and the free end protruding from the clamping device is turned, providing machining access to the entire surface of the rod section. U.S. Pat. No. 4,432,130, dated Feb. 21, 1984, to Leonard A. Gabriele, describes a "Six Station Broaching Machine", for sequentially machining multiple, parallel surfaces on workpieces. The workpieces are locked in position on an index table and the surfaces machined in one operation are angularly positioned with respect to the surfaces machined in a contiguous operation by revolving the workpieces about the axis of the table. U.S. Pat. No. 4,516,306, dated May 14, 1985, to Robert J. Albert, details a "Semi-Automatic Pipe-Threading Plant and Apparatus Therefor", including a lifting device for raising an unthreaded pipe to a height proper for a threading machine to form threads on each end of the pipe. A particular sequencing of equipment actuation and movement is utilized to facilitate loading of unthreaded pipe on the lifting device and unloading of threaded pipe, without requiring manual handling of the pipe. U.S. Pat. No. 4,655,652, dated Apr. 7, 1987, to Brian D. Schissler, describes a "Method of Multiple-Station Drilling" for performing a large number of repetitive, but variable machining operations. A turntable having multiple workpiece-holding fixtures distributed in spaced relationship around its periphery, includes multiple tool supports mounted around and outward of the periphery to provide a sequence of machining stations. A load/unload station is provided for reversably mounting workpieces on the fixtures and a motor is included for driving the turntable in an indexing fashion to bring workpieces held in the fixtures successively into registry with the machining stations. U.S. Pat. No. 5,042,125, dated Aug. 27, 1991, to Jon W. Harwood et al, details an "Apparatus for Manufacturing Stamp-Formed Mufflers". A muffler is assembled on an indexible fixturing apparatus having multiple stations for receiving the formed components of the muffler. A robotic gripping apparatus is provided in proximity to the indexible fixturing apparatus for moving aligned components of the muffler to welders and the aligned components are welded to one another while the pipes for the exhaust system are bent into their required configuration by programmable pipe benders. The assembled muffler and bent pipes are then delivered to a second indexible fixturing apparatus, on which programmable welders connect the exhaust system components together. U.S. Pat. No. 5,150,496, dated Sep. 29, 1992, to Scott Bromley, describes an "Internal Grinding and Cutting Device for Pipe and Casing" for reworking the interior diameter of oil field pipe and casing, and especially plastic-coated pipe that is to be re-coated. The device is characterized by a grinderhead with a cutterhead assembly, including a mandrel which turns a special cutting device having multiple grinders for engaging and cutting the inner wall of the pipe as the cutterhead assembly is forced to travel through the pipe. Alignment and grinding members are attached to the mandrel for maintaining proper alignment of the cutterhead assembly in the pipe.
One of the problems inherent in conventional workstock forming devices such as pipe nipple threading apparatuses and methods is the substantial amount of floor space required for the equipment. Additionally, the process of forming or threading multiple pipe nipple blanks on both ends can be extremely labor-intensive and slow, since the technique usually involves reversing the ends of the blanks. Accordingly, it is an object of this invention to provide an efficient, space-saving, automated method and apparatus for successively forming the ends of workstock, such as threading the exterior circumference of both ends of multiple pipe nipple blanks, without reversing the blanks.
It is a further object of the invention to provide a method and apparatus for threading and inspecting the exterior circumference of both ends of workstock such as pipe nipple blanks, which apparatus is characterized by computer-controlled, sequentially-activated components, including a loading cylinder for handling pipe nipple blanks, an indexible turntable fitted with a pair of clamping devices such as vises, connected by a guide slot or tube for receiving and stabilizing the blanks and a pair of threading spindles for threading the blanks at each end without the necessity of reversing the blanks in the handling apparatus. The forming or threading method includes successively loading individual unthreaded pipe nipple blanks onto the first vise on the indexed turntable by operation of the loading servo or cylinder, which turntable then rotates approximately 45 degrees and positions one end of the blank to be exteriorly engaged and threaded by a first threading spindle. The turntable then rotates back into loading configuration and receives a second nipple blank, which is similarly positioned and threaded, while simultaneously linearly forcing the first nipple blank into a guide slot or tube positioned across a diameter of the turntable. Sequential loading and threading of additional blanks causes the unthreaded ends of the first and successive nipple blanks to progress in the guide tube and align in sequence with a second vise and a threading spindle, the latter of which sequentially threads the unthreaded ends of the first and successive nipple blanks. The turntable again rotates, loads additional blanks and displaces the first and successive completely threaded nipples to a hopper or an inspection station, and the cycle repeats. The threading cycle may be controlled by a programmable controller for receiving data, either manually or from a computer.